One of the undisputed keys to the successful treatment of cancer is early diagnosis. This strongly argues for participation in routine screening programs. However, those that are in place currently suffer from significant drawbacks. A major thrust of applied cancer research in the coming years will be a search for improved diagnostic methodologies. One route toward the design of new surveillance methods is the identification of markers that are characteristic of tumor cells. The foundation of the proposed research is two-fold. We will use the Genetica trap technology to sift libraries prepared from colon, breast and prostate carcinomas for genes encoding trafficked proteins. Thereafter, we will use "off-the-shelf"technologies to assess differential expression of such genes in normal and tumor cells. These studies will lead to the creation of libraries of tumor-specific genes that encode secreted and cell surface proteins. These will be used to generate immunological reagents to analyze blood born and cell surface markers in order to identify proteins that are diagnostic of early stage tumors. PROPOSED COMMERCIAL APPLICATIONS: There are a multitude of commercial applications for the proposed research. Primary is the identification of blood-borne, tumor specific proteins that can be used for the development of routine diagnostic tests. In addition, we may identify potential targets for tumor imaging agents. Finally, tumor-specific receptors may be provide starting points for the development of small-molecule anti-tumor drugs or biotherapeutics.